Wednesday, September 26, 2012

How Much Protein is Enough?

By: Anne Guzman, PCG Nutritionist

A good nutrition plan includes proper amounts of each macronutrient (protein, carbohydrates, fat). Athletes need to fuel their training and to give their bodies these nutrients to perform, repair and recover properly. On top of this an athlete needs also to think about their overall general health, which includes a strong immune system. 

One area that I find is still largely misunderstood even though well studied is the area of protein for endurance athletes. Most of my clients come to me with nutrition regimes that include too much protein and fat and not enough carbohydrates (their main fuel source). There is this fear that we need MORE protein, but in reality, excess doesn't benefit the endurance athlete. 

Research indicates that endurance athlete should consume a diet of approximately 55%-60% carbohydrates, 20-25% fats and 15-20% protein (1). This clearly has some flexibility and we need to also consider grams of carbohydrates per kg of body weight as well as percentages when making a detailed plan. Also some endurance athletes, such as Kenyan marathon runners, have reported consuming up to 70% carbohydrate diets. 

However, with the billion dollar diet industry pushing Lower Carbohydrate and Zone-esque like diets, some athletes still seem to have jumped onto the higher protein, lower carbohydrate bandwagon. Whether it is in an attempt to lose weight or simply because media has led them to believe this is what they need to lose weight, it is a mistake. Although we do need protein, it is not the endurance athlete’s fuel of choice. These diets are a recipe for disaster for the endurance athlete.

The bottom line for endurance athletes is that carbohydrates and fats are the necessary fuels for energy. In the sports nutrition community carbohydrates are often said to have a “protein sparing effect.” What this refers to is that we should eat approximately 55-60% carbohydrates in order to spare the protein for its routine uses in the body. Protein is required to make antibodies for the immune system; it builds tissues (hair, nails, skin, and muscle) and amino acids make enzymes and hormones. Protein is also required to make hemoglobin which is needed to transport oxygen to the exercising muscles. 

If we do not eat enough carbohydrates, we will have to break down protein within body tissues as a source of fuel. This is very inefficient. When the body has to resort to protein for fuel it will rob the body of protein needed for its many important uses noted above. Protein has a slow gastric emptying rate (stays in the stomach longer) and therefore is not the food of choice while on the bike either (although protein in small quantities in sports drinks is still up for debate).

What is important to remember is that protein is NOT a big source of fuel during exercise. Even if you consume more, this will not change. “Based on nitrogen balance it can be estimated that protein contributes about 5%-15% to energy expenditure at rest. During exercise, in relative terms more amino acids may be oxidized. In relative terms, however, protein as a fuel is not important because of the much greater increase of carbohydrate and fat oxidation, which are your main fuel sources during exercise. Therefore, during prolonged exercise the relative contribution of protein to energy expenditure is usually much lower than it is at rest, usually well BELOW 5%! In extreme conditions when carbohydrate availability is limited this can rise to 10%” (1). Therefore you can see why endurance athletes will not benefit from higher than recommended protein diets. 

The recommended daily intake of protein for the average person is 0.8 g/kg body weight. For endurance athletes, the recommended intake is 1.2 to 1.8 g/kg body weight. Studies show that endurance athletes need 1.2-1.4 g/kg body weight to maintain nitrogen balance. Excess protein will not help cyclists perform optimally. In fact excess protein is simply stored as extra calories as fat. 

There are two schools of thought. Some researchers believe there is no need to increase protein more than the average person, 0.8 g/kg. The other school recommends the range mentioned above, 1.2-1.8 g/kg. One interesting observation scientists have made is that training seems to have a protein sparing effect in that the better trained an athlete is, the less protein oxidation occurs (2). This again supports that we do not require excess protein in the diet and may be fine with the amounts recommended to the general population of 0.8 g/kg. I believe that different individuals can succeed with different ratios of protein and for the most part athletes are not having any troubles meeting the bare minimum. Personally I’d aim for between 1.2-1.8 g/kg. If your immune system is consistently strong and your overall health is excellent and you are within the above ranges, you are on the right track. But why leave anything to chance if your goal is to be a champion?

As athletes the timing of your protein intake is crucial. For example post-workout protein intake in combination with high glycemic carbohydrates can increase protein synthesis. The timing is important here and you need to consume the meal within the first hours post-training. Studies suggest that ingesting 6-10 grams of protein post workout in combination with the proper amount of carbohydrates for your weight/kg is enough for optimal protein synthesis. 

The type of protein is also important. Whey protein for example is easily digested and superior to soy protein. It also makes for a simple post workout option in a smoothie. By combining carbohydrates and protein you not only refuel your glycogen with the carbohydrates, but they also create an optimal environment for absorption of amino acids. “Increased availability of glucose and amino acids also results in increased plasma glucose concentrations, which in turn may cause a reduction in protein breakdown and a small increase in protein synthesis.” (2) 

Chances are you are already eating protein within the endurance athlete recommended range of 1.2-1.8 g/kg. Even Tour de France athletes whose diets have been closely followed (some eating 7000-9000 calories a day) are able to meet their protein needs simply due to the increase in overall caloric intake. As noted above we tend to forget that almost all foods have some protein in them. Generally speaking there is a linear relationship between energy intake and protein intake and if you are matching your energy expenditure for the day you should not have to add protein supplements to your diet. Having said this whey protein powders are often used for convenience and for their easy digestion. I personally have most of my athletes having some type of smoothie on most days of the week as it is an easy way to get a lot of nutrients. 

The bottom line is that protein is necessary for the active athlete, but more is not necessarily better. Get the timing right, get the grams per kg right and journal your nutrition for a few days so that you can be sure you are consuming the proper amount for your diet. Or hire a professional Sports Nutritionist to do the work for you.

I know you will get your hours in on the bike this week, but will you refuel your tank with the right fuels in the proper amounts to get the most return from those hard training hours? If you want to have the most powerful 2012 yet, the answer to this question should be a resounding YES! 

1. Ryan, Monique. Sports Nutrition for Endurance Athletes-Second Edition. Velo Press, March 2007
2. Jeukenrup, Asker. Gleeson, Michael. Sport Nutrition-Second Edition. Champaign, IL; Versa Press, 2010.

This article has been reprinted from Pez Cycling News Online.  Anne Guzman is a regular contributor to Pez Cycling News Online.